Venus has some significant advantages over Mars,especially if your goal is to create extra-terrestrial Earth-like habitats whose inhabitants can easily visit or return to Earth without suffering any problems with Earth’s strong gravitational field: Venus’ gravity is closer to Earth-normal than anyplace else in the solar system.*

As all the pro-Venus folks have pointed out, you don’t even bother trying to survive the hellish surface of Venus, you establish dirigible-like and barge-like habitats and structures that can propel themselves (at a stately pace) through the upper atmosphere of Venus, where the atmospheric pressure is right around one bar (1 bar, or 1000mbar, is roughly sea-level air pressure on Earth), so that you can keep pace with the slow rotation of the planet and stay on the sunny side at all times, so your crops keep growing and your solar panels keep working. Nearly all the nasty heat and sulphuric acid is all well below you. Interesting hydrocarbons and gaseous elements can be harvested relatively easily from the various levels of Venus’ atmosphere.

However… when you were a kid, did you ever play that game in which the floor of a room is lava, and you have to get around by staying up on the furniture all the time? And if you ever touch the floor, you “die”? That’s very much what it’s like to descend from orbit and land on one of these balloonist barges. SpaceX makes it look easy these days, and perhaps it usually would be. But if there’s a problem, there is no place else to land safely. With nearly Earth-normal gravity, an abort-back-to-orbit is not possible once you’re no longer hypersonic, and possibly not even then. And when you’re on final approach,you simply cannot miss the landing pad, or you die.And if you miss the pad and set down on a hab, or damage the structural integrity of the dirigible holding up that section of the colony, you get aDave ConsiglioandEveryone Dies.

Don’t dismiss this challenge offhand. Think about it carefully:every place that you’re able to stand, or set something down,you’ll need to carefully engineer and constantly manage its buoyancy/altitude, its “trim” (so the whole thing doesn’t rock like a dory when you walk around on it or shift mass back and forth, which you’ll be doing all the time), chart its course, etc.Every “unimproved” square inch of the planet at those pleasant altitudes is an abyssfrom which no fallen person or dropped object can be retrieved. Everything falls straight to hell—in as literal a manner as you can imagine.

Also… one of the biggest reasons given for establishing any sort of human presence on any celestial body with an appreciable gravity well (any planet or spherical moon) is that you haveeasy access to all the mineral and elemental resources on that body: water (usually ice, sometimes liquid or even steam), minerals of all sorts in vast quantities, etc. Having any sort of atmosphere is icing on the in-situ-resource cake. But a colony on Venusonly has easy access to the atmosphere.A very nice atmosphere, quite complex and interesting to be sure, but zero access to surface/mining resources, which are all trapped down there in hell.

In contrast,Mars’ lighter gravity means a larger window of opportunity to “abort-to-orbit”if something goes badly wrong during re-entry, andif you miss the landing pad by a hundred meters or even a hundred kilometers, chances are good that you’ll be able to land on level ground anyway,not plunge into an abyss and go straight to hell.

Mars’planetary resources are not confined in a raging crushing acid-furnace helllike Venus’. Plus it does have auseful atmosphere— not much of one, and a relatively simple one, compared to Venus, but 96% of it is a precious gas we want to use for rocket fuel production, for greenhouse pressurization, for oxygen we’ll need to breathe, and for all sorts of useful kinds of chemistry and metallurgy that any actual colony is going to need.Getting persons and goods off-planet is vastly easier from Marsthan from a launch pad (or perhaps a launchhammock?) floating at altitude on Venus: sure, it’s a high altitude launch, but not high enough to appreciably diminish the pull of Venus’ gravity. (That’s why humans will be comfortable living at that altitude, remember?)

Plus there’s a lot to be said for living onterra firma, not hovering over a hellish abyss.You can drop a toolon an EVA and just bend down and pick it up again;you can stumble and fall, clamber to your feet, brush the dust off your knees (or your bum, your shoulder, whatever), and blithely get back to work. And if a tragic accident does occur—a lander crashes, a hab ruptures and loses pressure, a rover topples over a cliff—at least there’s wreckage to examine, survivors to rescue, valuable debris to recover.

It hasn’t all vanished, swallowed up in a Venusian hell.

*Remember that little asterisk at the beginning? If you really want perfectly Earthlike conditions, and you’re prepared to engineer and artificially construct every square inch of them and all the cubic meters of gear and mass necessary to support each square inch of them,the sensible alternative to Venus is something likeKalpana One.It’sa design that solves the stability problemsthat plagued the O’Neill Cylinder and other popular orbital habitats suggested in the 1970s, ‘80s, and ‘90s.

This questionoriginally appeared on Quora - the place to gain and share knowledge, empowering people to learn from others and better understand the world. You can follow Quora on Twitter, Facebook, and Google+. More questions: